With an increasingly finer structure of a semiconductor device, the formation of an interconnect pattern smaller than a critical dimension of the resolution of lithography is demanded. The sidewall transfer technology is known as a technology to form a fine interconnect pattern.
According to the sidewall transfer technology, a pattern having a dimension smaller than the critical dimension (a line width or pitch) of the resolution of lithography can be formed by a pattern transfer using a formed sidewall film as a mask.
A technique to form a pattern having a dimension less than half the resolution limit of lithography by repeating a sidewall transfer process a plurality of times is also proposed.
For example, a line & space pattern like a pattern of a memory cell of a flash memory is formed by the sidewall transfer technology. A contact pattern is formed so as to be connected to an interconnect pattern (line pattern) led from a memory cell array in a region to connect a peripheral circuit and the memory cell array. The dimension of the contact pattern is preferably larger than the dimension of the interconnect pattern.
However, it has been difficult to form a contact pattern having different dimensions from those of a line pattern in a process common to a manufacturing process to which the sidewall transfer technology to form a line & space pattern is applied.